The germula kingdom: rainbow germ
At the microscopic level the oceans, rivers and soils are teeming with life. Much of the bulk of this is composed of organisms belonging to the germulaic kingdom.
The basic physiology of the germula cell
Germulas are fairly simple single celled organisms with an average size of 200-400μm (though there are much larger and smaller examples at the extremes) with a basic internal structure. The cells are defined by having a cell wall whose composition varies between species, which is often tough and flexible. Cilia and flagella often protrude beyond the cell wall and are used for locomotion. Many species support this cell wall with an internal structure, often composed of different materials to that of the cell wall.
Within the cell wall is found an inner membrane known as the cell membrane, whose functions vary but usually include controlling the transportation of molecules across the cell wall and managing chemical balances between the cell matrix and the outside wall. It also plays a role in energy metabolism, particularly energy production (chemically or photosynthetically) and the building of storage granules (typically starches).
A second series of membranes - reactive membranes - can be found throughout the cellular matrix, often wound around the support structures. These are closely associated with the production of many types of proteins and other materials used to build and maintain the cell, and proteins associated with detection of external stimuli. They also play a key role in the transporting of materials across the cell, including signalling chemicals.
Germulaic DNA is gathered together into structures known as pseudo-chromosomes - in which rings of DNA (toruses) are aggregated together into much larger clusters that are transferred to the next generation as single units. Control mechanisms are largely seperated from genes and triggers, and non-coding structural elements also make up a significant part of the pseudo-chromosome. Unlike the DNA toruses found in brothic and microfilm organisms, pseudo-chromosomes will be closely associated with membranes and other structures within the cell matrix; they are not separated from the rest of the cell by membrane envelopes, as occurs in vermic and chimeric organisms.
Many germulaic species will posess more than one pseudo-chromosome - in these organisms one bundle is always be found embedded within the reactive membrane; this active pseudo-chromosome controls the biochemical activity of the cell. The purpose of the other bundles (if present) will vary between species - sometimes they are used during sexual reproduction, or in some species for the hijacking of other cells. Scientists have reported that in a few species the additional pseudo-chromosomes will compete with the active pseudo-chromosome for control of the cell.
Individual germula organisms do not exist in isolation. Rather thay have a proactive relationship with other cells of the same species and of other species, forming a complex web of predation, cannibalism and parasitism. All germula species posess protective granules which float freely within the cell matrix. Some scientists have argued that these granules were originally free-living species of germula which have evolved a symbiotic relationship with their host. There are probably as many types of protective granulas as there are germula species, varying in complexity from simple strands of RNA with a few associated proteins to pseudo-cells that have (according to the theory) lost the ability to survive or reproduce outside of the host cell. They all have a key role in defending the host cell from hijack or predation by other cells, and many are capable of other functions such as more efficient waste management or more complex energy storage mechanisms.
The rainbow germ
One of the most intensively studied germula species is the Rainbow Germ. This is an organism commonly found in estury muds, noted for its wide tolerance to changes in salinity and its propensity to grow an internal structure using metalled silica (a silicon dioxide matrix within which can be embedded atoms or molecules of various metals - in particular nickel and copper, and less frequently palladium, silver, platinum and gold). The major component of its cell wall is cellulose, with bands of acetated cellulose spiralling from the base of the cell to its tip. A flagella with two strands twice the length of the cell (up to 800μm compared to an average cell length of around 450μm) is located at the posterior end of the cell.
The organism is so common in some esturies that accretions of dead cells form deep sandbanks. Ancient strands of organisms similar to the Rainbow Germ have been mined in some areas, principally to extract copper and nickel.
The organism obtains most of its energy from photosynthesis, principally from the shorter visible wavelengths, giving the cell a green-red shimmer when observed under the microscope - hence its name. It uses the energy to produce a range of starches which are stored throughout the cell matrix in storage granulas, with a particular concentration of granulas around the flagella root and the cell spike.
A typical cell will possess two DNA pseudo-chromosome bundles, composed of 8 rings of various sizes joined together by a ninth DNA ring which appears to have a purely structural role. The pseudo-chromosomes do not appear to compete for control of the cell; instead one bundle acts as the active pseudo-chromosome controlling day-to-day metabolism, while the other controls both sexual and asexual reproduction (and is thus known as the sexual pseudo-chromosome). Both bundles possess a complete inventory of the organism's genetic code.
The rainbow germ is an opportunistic parasite of a number of closely related, and a few more distantly related, germula species. In addition to being able to reproduce asexually by simple division, the organism is also able to hijack the cells of related species.
The hijack strategy follows a similar pattern to sexual reproduction between rainbow germ organisms. When two rainbow germ cells come together to mate they mutually transfer their sexual pseudo-chromosome to the other cell via the cell spike. The transferred pseudo-chromosomes then undergo a quasi-mitotic gene swap with the resident active pseudo-chromosome, mediated by a sexual membrane grown specifically for the purpose. Once the swap is completed the implanted pseudo-chromosome is destroyed and the active pseudo-chromosome produces a new pseudo chromosome from the remnants of the old.
In a hijacking situation, the rainbow germ will attack the victim cell; the cell spike plays a crucial role in this process. The tip of the spike is packed with enzymes and RNA snippets which, on being injected into a new cell, rapidly attack and destroy the resident DNA structures. Once this is achieved, the sexual pseudo-chromosome enters the cell and immediately begins to reorganise the cell contents and structure to meet its requirements. Membrane building takes precedence over structural changes and the hijack can take several days to be completed, by which time the pseudo-chromosome will have produced a copy of itself to act as a new sexual pseudo-chromosome. When two rainbow germs attack each other (mate), they usually manage to neutralise the other cell's enzyme attack.
Many hijack attempts fail, and the rainbow germ is in a constant spiral of evolution with its prey as it develops new enzymes and DNA snippets to overcome the attacked cell's defences. The protective granules, which consist of between 6 and 12 well developed organelles (the primary protective granulas) and a separate granule set of proteins and mixed nucleic acid chains (the secondary protective granulas), play a lynchpin role in the rainbow germ's own defence system.
The impact of germula species on humans and cultivations
As a species, the rainbow germ is fairly benign when considering its impact on Type Two lifeforms - while it is populous, found in large numbers in river and estury muds, it rarely attacks Type Two lifeforms. Scientists have long understood its role in triggering river hives - a rash that affects some people who come into contact with heavily populated muds and soils. The river hives rash is itchy and lasts for no more than a couple of days; it is in fact an allergic reaction triggered by a person's immune response to chemicals on the surface of the rainbow germ's cell wall. Very rarely such contact will lead to a severe allergic reaction and, in very rare cases, lead to anaphalactic shock and even death.
Other germulaic species are, however, less benign. A number of species are opportunistic hunters capable of consuming Type Two microflora - these represent a serious risk to soil cultivations and, if left untreated, can lead to soil souring and soil death. Other species can directly attack plants, animals and people, leading to lesions which may then fall open to other, secondary infections which lead to the death of the organism. Historical plagues such as the strangling death and the sweating plague have been traced back to germulaic attacks where the infections were transferred between people - in the case of the strangling death the germula cells moved from person to person in the aerosol produced by people struggling to breath as the throat and trachea constricted in the latter stages of the disease.